As a background art of the present technical field, “an exhaust emission control apparatus capable of improving combustion efficiency of particulate substances deposited on a filter without causing an excessive temperature rise of the filter” is known (for example, refer to PTL 1).
PTL 1 describes “the exhaust emission control apparatus includes a filter provided in an exhaust passage of an engine to capture particulate substances contained in exhaust, an exhaust throttle valve interposed in the exhaust passage of a downstream side of the filter, a concentration acquisition unit acquiring an oxygen concentration in the exhaust flowing into the filter, a temperature acquisition unit acquiring a carrier temperature of the filter, and a control unit controlling an opening of the exhaust throttle valve, on the basis of the oxygen concentration acquired by the concentration acquisition unit and the carrier temperature acquired by the temperature acquisition unit, at the time of regenerating the filter” (refer to [Claim 1]).
In addition, “an internal combustion engine control apparatus capable of surly avoiding occurrence of an excessive temperature rise of a PM filter in a stoichiometric burn engine including the PM filter in an exhaust passage” is known (for example, refer to PTL 2).
PTL 2 describes “the internal combustion engine includes a particulate filter trapping particulate substances contained in exhaust gas in the exhaust passage and the internal combustion engine control apparatus executes a stoichiometric burn operation using control to realize a theoretical air-fuel ratio as basic control of an air-fuel ratio. The internal combustion engine control apparatus includes a fuel cut control unit executing fuel cut at the time of deceleration of the internal combustion engine, a filter OT determination unit determining whether the excessive temperate rise of the particulate filter occurs by execution of the fuel cut, and a fuel cut prohibition unit prohibiting execution of the fuel cut at the time of deceleration, when it is determined that the excessive temperate rise of the particulate filter occurs” (refer to [Claim 1]).